Hydraulic hoisting device.



G. A. WOOD.

HYDRAULIC HOISTING DEVICE.

APPLICATION FILED MAR. I5, l9l5. RENEWED AUG. I. 1917.

Patented July 9, 1918.

2 SHEETSSHEET1 IL. 1% M M W D G. A. WOOD.

HYDRAULIC HOISTING DEVICE.

APPLICATION FILED MAR.15. I915- RENEWED AUG. 1,1917- Patented July 9, 1918.v

2 SHEETSSHEET 2- ing the piston to the GARFIELD a. W001), or nnwnorn iutcmean.

HYDRAULIC nors'rrn e'nnvron,

Application filed March 15, 1915, Serial No. 14,480.

To all. whom, itmay concern Be it known that I, GARFIELD A. Woon, a citizen of the United; States, residing; at Detroit, in the county of Wayne and State of Michigan, have invented: a new and, useful Hydraulic Hoisting. Device, of which the following is a specification.

It is common practice to tilt the bodies of motor vehiclesv about pivots located near the rearend of the-chassis in dumpingv coal or other: material. therefrom, and liquid op erated hoisting pistons have been used heretofore for. that purpose. The distance the end of the body must be elevated is con -v siderable, whieln together with the. heavy; loads and tendency of thebody to swing laterally when elevated (due to twisting of the-frame of the chassis when standing on an uneven surface), as well as-the. generally rough usage to which the devices. are otherwise subject, often cause bending of the piston rods. The present invention contemplates the use of a hollow piston rod instead, of the ordinary solid rod, whereby much greater capacity for resisting bending stresses is secured without. increasing theweight. The invention also aimstoutilize the'space above the piston between the piston, rodand the. cylinder, as well as the interipr of the rod. itself, as a reservoir for. the liquid (oil,;preferably) and it includes means for. venting. the upper end of thehollow. pistonrod on. the. hoisting stroke and; for preventing the escape ofv liquid; therefrom as. the piston approaches the end of the down-stroke. Other features. of the invention: reside. in improved means for so curing the piston to the piston 'rod, and, for mo n ing: a c o p e e l h pp i the piston in position to support elements (as shown, sheaves an free end of the body, or any otherload.

In the drawings, Figure 1 is afragmena tag-y. side view of a motor truck showing. one embodiment of my invention, the forward; end of the hoisting cables. and their anchorage being omitted. Fig. 2, is a front elevation corresponding to Fig. 1, parts being omitted-. Fig. 3 is a vertical longitudi nal-section through the hoisting cylinder. Fig. 4 is a section of the upper end of the piston at right angles to Fig. 3. Fig. 5: 1s a sectional view showing a modified orm of venting 'means for the-piston rod. Fig. 6

Specification .of Letters Fatent.

body amay. be ingpunposes, and the body may be provided d cables) for connect Renewed-Maud 1, 1917, Serial Ito. 18%,979.

is a fragmentary section on the line 6-6 of. Fig. 1.

Similar referencecharacters -refer to like partsthroughout the. several views.

Upon. the, rear end of-. each of the side frames. 1 of the truck is rigidly secured a bracket Qbearinga pivot 3- about whichthe swungvertically. for dumpat: its lowenside w th the longitudinal frame pieces 5,s o ,arranged as.to rest, when in,1ow-

eredr positlon,

eithen on the side. frames 1; or in special shown). This general. construction is well. known.

The side frames maybe cut away at a point: forward of the front end of the body as indicated. at 6, and; may there support the cross bars 8" (preferably angle-ironshaving. their horizontal flanges facing each,

Patent d ulr. 99 1918 chairs carried. .thereby (not, I

other) upon which rests the flanged base 9 v of a hoistingcylinder- 10, the latterof which may, be inclined rearwardly andsecured to the base by a screw joint 11 (Fig. 3). At its uppenend, the cylinder may pass through an expansion chamber or tank 12 which. is

in fneecommunication with the interior of the. cylinder-by means of. the lower passage 13, and the. upper passage 14:. The filling opening of-the chamber is closed by a plug, 15, and in, the bottom is a gland 16. whereby a discharge pipe 17 may be clampedin place. Various means; may be employed for securing.- theexpansion: chamber in position; as shown, the upper end. of the cylinder is reduced to, form, a seat 18 (preferably. conical) against which the. chamber is clamped by. afiange19of a stuffing box 20'threaded into the. interior; of the upper end of the cylinder at i 21. v

"Mounted to slide in the box 20 is a hollow piston rod 2 2, thev upper end of which. is closed by; a, diaphragm 2. L; the lower end of the. rod is. preferably. threaded on the annular shoulder. 25. of, a'piston 2.6, which may. beprovided with the usual piston rings 28. The piston, ma. have projecting. from its lower endthe stud 29'that contacts with the. base. and carries the weight when in. lowered sition. Free passage of liquid between t e inside of the rod and the annular. space around it is secured by the holes SOjust above the piston, whereb the interiorof the ,rodmay also be utilized for storage purposes. And. inorder to admlt air-to the upper end of the rod to allow the liquid to pass out into the cylinder as the piston rises, there is provided a tube 31, the upper end of which is just below the diaphragm, the lower end openingthrough the piston wall somewhat below the stuflin box when the piston isin lowermost position. This arrangement of the parts is particularly important in that it prevents any escape of oil as'the piston'rod sinks. The construction is also extremely cheap andreliable. The joint between the piston rod and the box'20 may be sealed by the threaded packing ring 33 and the packlng 34.

It will be understood that the liquid by which the piston is elevated is normally stored in the annular space above the piston, in the hollow. 'rod and in the expansion chamber. Obviously, it may be pumped from the storage space to the pressure space beneath the piston by various devices, but

- it is preferred to use a gear pump 36 bolted or otherwise secured at 38 to the base 9 and driven from the propeller shaft 39. of the vehicle by means of clutch mechanism 40 controlled by the levers 41, link 42' and lever .43. The valve shaft of the pump is shown at 44 and may be operated by the lever45, link 46 and lever 47. The reservoir discharge pipe 17 previously referred toleads to the intake fitting 48 of the pump, and liquid is discharged into the'sp-ace beneath the piston through the passage 49; As indicated in Fig. 6, the interior of the pump casing may be provided with the passage 50 that leads from the suction side to the pressure side of the gears 5'152 (through the latter of which the propeller shaft passes) and'is connected to the pipe 17 by the passage 53. It is also connected to the passage 49 by the three-way valve 54 rigid with the valve shaft 44. r

The use of the hollow piston allows a cross-bar 60 to be firmly supported by being passed through a hole in the upper'end of the rod. Each end' of the cross-bar is grooved at 61 to receive a shackle 62, portions of which extend downwardly from either side of the bar to support a pivot pin 63, uponthe latter of which a second shackle 64 bearing the shaft 65 and pulley 66 is adapted to swing. Secured to the base 9 or other fixed part of the hoist is a shackle 68 storage purposes.

relation to the seat as the liquid sinks by a stem 78 and cross-piece 79.

Operation.

The parts are normally in the position shown, the upper level of the oil (or other liquid) being considerably below the upper wall of the chamber 12 in order to allow for expansion. As the liquid is subjected to violent churning or agitation by the pump it soon heats and tends to become frothy and of greater volume, and the lighter or more frothy parts, if allowed to be drawn back to the pump, would greatly impair its op-'- oration; the chamber 12 is, therefore, as shown, made of such size as to allow for the expansion of the liquid and the accumulation of the light frothy portion in the space above the current of liquidthat passes from the interior of the cylinder to the pipe 17in-other words, above the passage 13.

.The drawing off of the liquid through this chamber eliminates any necessity. for additional piping and connections, which would be difiicult to apply to the thin cylinder. When it is desired to hoist the load, the

clutch lever and pump valve are manipu-- lated in the proper manner and oil is drawn from the reservoir and forced beneath the 7 piston. As soon as the piston has been elevated a distance suflicient to cause the lower-- end of'the tube 31 to clear thepacking ring 33, air rushes in through the tube and the contents of the rod thereafter runs out into the annular space surrounding it and is delivered to the expansion tank as the piston rises. This action maintains a liquid seal float 76. -The valve is retainedin operative over the entrance to the pipe 17 and prevents air from being sucked into the pump. The piston may be lowered by turning the pump valvein position to allow the oil to escape back through the passage 49 and pipe 17 into the tank cylinder and piston rod without passing through the gears 51-52, the air escaping through the tube 31. However, before the liquid can possibly overtop the tube, the lower end of the latter will have passed into the packing ring 33,

thus preventing any of the liquid from escaping. Since the upper end of the tube is located just beneath the diaphragm, the liquid may rise until substantially the. en-. tire capacity of the piston rod is utilized for When it is desired to lower the body, the valve 54 is turned into the'position shown (Fig. 6) which'allows the liquid to by-pass the pump gears.

It will be observed that the upward movement of the piston is automatically limited by the port 13; in'other words, as soon as thepiston rises above the port ,the liquid circulates in an endless loop, one limb of.

which includes the pipe 17 and the pump while the other includes the passage 49 and venting the air and more frothy and com pressible elements of the oil from getting into or continuing in circulation, which would impair the efiiciency of the hoist. By providing the port 13, the necessity of throwing out the clutch or shutting down 'the engine as the piston approaches the upper end of the cylinder is obviated. It will also beseen thatwhen the piston is at its upper limit of movement both branches of the loop are in communication at substan tially their highest point (through the pas sages 14 and 30 and the pipe 31) with the atmosphere. Putting it another way, the space below the piston is then in communication with the atmosphere through the passages 13 and 14 and the interior of the rod. Besides freeing the liquid of froth, as stated above, the piston is therefore prevented from becoming, locked in its uppermost position.

It is clear that many changes may be made inthe details of construction without departing from the spirit of my invention. I do not, therefore, wish to be limited otherwise than as indicated by the subjoined claims.

I claim 1. Hoisting mechanism comprising a cyl-- closure extending across and fixed to thepiston rod at a point near its upper end, the interior of the piston rod being in communication with the atmosphere at a level somewhat below the closure, and means for transferring the liquid from. the storage space to the space between the lower end of the cylinder and the piston whereby the piston and piston rod are caused to rise.

2. Hoisting mechanism comprising a cylinder having an upper and a lower end, a piston slidable in the cylinder, a hollow piston rod connected to the piston and having its upper end passing out through the upper end of the cylinder, said piston rod being in communication near its lower end with the interior of the cylinder above the piston to form storage space for liquid, an imperforate closure, fixed to the piston rod, for the upper end of the latter, means for transferring the liquid from the storage space to the space between the lower end of the cylinder and the piston whereby the piston and piston rod are caused to rise, and means for admitting air to the interior of the cylinder as the piston rod rises and forpreventing the escape. of oil therefrom as the piston approaches the limit of 1ts down-stroke.

3. Hoisting mechanism comprising a cylinder arranged with one end above the other, a piston and piston rod slidable therein, said piston rod being hollow whereby 1t constitutes storage space for liquid, means for transferring the stored liquid from the interior of the piston rod to the space between the lower end of the cylinder and the piston to cause the piston and the piston rod to beelevated, means for transferring the liquid back into the piston rod from the space beneath the piston, a closure for the upper end of the piston rod, means for admitting air to the interior of the piston rod at a point below the closure as the piston rod rises and for preventing the escape of oil therefrom as the piston approaches the limit of its down-stroke, there being an unobstructed passage through the hollow piston rod from the lower portion thereof to the closure to allow the liquid to freely rise and fall.

4. Hoisting mechanism omprising a cylinder, a piston slidable t erein, a hollow piston rod connected to the piston and spaced from the cylinder, a closure for one end of the cylinder,said piston rod passing through the closure, means for closing the 'end ofthe piston rod'remote from the piston, the interior of the piston rod being in communication with the space between the piston rod and the cylinder to form a storage space for liquid, means for transferring the liquid from the storage space to the opposite side of the piston to cause the latter to slide in one direction, and means for venting'the closed end of the piston rod, said means comprising an air conduit, one end of which is located within the piston rod and in proximity to the closure therefor, the other end opening laterally through the wall of the piston rod at a point more removed from the closure whereby air is admitted to the piston rod as the latter is forced through the cylinder.

5. Hoisting mechanism comprising a cylinder having one end arranged above the other, the lower end being closed and the,

upper end being reduced to form a shoulder, a storage tank for liquid carried by and surrounding the cylinder, means for clamping the tank rigidly against the shoulder to prevent leakage, a piston and piston rod slidable in the cylinder, and means for transferring liquid 'from the storage tank to the space between the lower endof the cylinder and the piston for causing the latter and the piston rod to be elevated.

6, Hoisting mechanism comprising a cylinder having one end arranged above the other, the lower end being closed, a piston and piston rod slidable within the cylinder, said rod being of lesser diameter than the interior of the cylinder whereby an annular storage space for liquid is formed, a storage tank for liquid carried by the cylinder, said tank being in communication with the annular storage space, at two different levels, and means for transferring liquid from the storage tank to the space between the lower end of the cylinder and the piston for causing the latter and the piston rod to be elevated. r

7 A cylinder, a member reciprocable therein, said member including a piston and,

the piston rod and in proximity to the closure therefor, the other end opening laterally through the wall of the piston rod at a point more removed from the closure whereby air is admitted to the piston rod as the latter moves through the cylinder in the direction stated, and whereby liquid is prevented from escaping from the piston rod as it approaches the end of its movement in the opposite direction.

8. A cylinder, a member reciprocabl therein, said member including a piston and a hollow piston rod connected to the piston and spaced from the cylinder, said cylinder including a closure for one of its ends, said piston rod passing through the closure and forming a storage reservoir for liquid, said reclprocable member including a passage through which the stored liquid may escape as the reciprocable member moves in onedirection, means for excluding air'from the piston rod during the early portion of the movement. in th direction stated, and means for admitting air to the interior of the piston rod when it has moved a predetermined distance in the same direction.

9. A cylinder, a member reciprocable therein, said member including a piston and a hollow piston rodconnected to the piston and spaced from the cylinder, said cylinder including a closure for one of its ends, said piston rod passing through the closure and forming a storage reservoir for liquid, said reciprocable member including a passage through which the stored liquid may escape as the reciprocable member moves in one direction, a closure for the end of the piston 10. A cylinder, a member reciprocable.

therein, said member including .a piston and a hollow piston rod connected to the piston and spaced from the cylinder, said cylinder including-a closure for one of its ends, said piston rod passing through the closure and forming a storage reservoir for liquid, said reciprocable member including a passage through which the stored liquid may escape as the reciprocable member moves in one direction, a closure for the end of the piston rod remote from the piston, said piston rod having a passage through its wall at a point near the closure, th whole arrangement being such that the entrance to the last mentioned passage is inclosed by the cylinder to exclude air from the interior of the piston rod during the early portion of the movement of the latter in the direction stated, and is afterward uncovered to allow admission of air thereto. a,

11. Hoisting mechanism comprising a cylinder having an upper end and a lower end, a closure for the lower end of the cylinder, a closure for the upper end of the cylinder, a piston and piston rod slidable in the cylinder, said piston rod passing through the last named closure, means for formin an expansion chamber at the upper end 0 the cylinder, said chamber being in communication with the upper end portion of the cylinder at two different levels, and means for transferring liquid from the expansion chamber to the lower end portion" of the cylinder to raise the piston and piston rod.

12. Hoisting mechanism comprising a cylinder having an upper end and a lower end, an annular closure for the upper end of the cylinder, means for forming an expansion chamber exterior to the cylinder at the upper end portion of the-latter, said expansion chamber being in communication with the interior of the cylinder through a passage in the wall of the cylinder at a point some distance below the upper end of said wall, means for drawing liquid from the expansion chamber and discharging it into the cylinder below the piston for elevating the latter, whereby the upward movement of the the cylinder, said tank being in communication with the upper portion of the cylinder at two different levels, said tank having an opening through which liquid may be poured for filling purposes and whereby air is allowed to escape from the storage space in the 'filling operation.

14. Hoisting mechanism comprising an" upright cylinder, a. piston and a hollow piston rod slidable in said cylinder, sealing means for the upper end of the cylinder, the piston rod passing through the sealing means, the piston rod being in communication near the piston with the space between the rod and the cylinder, means for forming an expansion chamber atthe upper portion of the cylinder, and means for drawing liquid from the expansion chamber and forcing it into the space below the piston to elevate the latter.

15. Hoisting mechanism comprising a cylinder having an upper end and a lower end, a closure for the upper end of the cylinder, a piston and piston rod slidable in'the cylinder, said piston rod passing through the closure, means for forming an air chamber at the upper end of the cylinder of size sufficient to allow expansion of an amount of liquid sufiicient to fill a large proportion of the space inclosed' by the cylinder, said airchamber forming means being supported by the cylinder, a closure for the lower end of the cylinder, and pump means for drawing off the liquid from above the piston through the air chamber and delivering it to the space in the cylinder below the piston whereby the piston rod is projected from the upper end of the cylinder.

16. Hoisting mechanism comprising a cylinder having an upper end and a lower end, a closure for the upper end of the cylinder, a piston and piston rod slidable'in the cylinder, said piston rod passing through the closure, means for forming an air chamber at the upper end of the cylinder of size sufficient to allow expansion ofran amount of liquid sufiicient to fill a large proportion of the space inclosed by the cylinder, said air chamber forming means being supported by the cylinder, pump means for drawing liquid from the upper portion of the cylinder and expelling it into the lower portion thereof below the piston, and means for automatically allowing the liquid below the piston to escape back to the pump means when the piston nears the upper end of the cylinder, whereby the pump means may run continuously.

17. Hoisting mechanism comprising an upright cylinder, a closure for the lower end of said cylinder, an iinperforate piston slidable in said cylinder, a hollow piston rod secured to said piston, an annular closure for the upper end of the cylinder, said piston rod projecting through the closure, a passage connecting the lower end of the rod with the space surrounding the rod above the piston, whereby the space both outside and inside of the piston rod may be used for the storage of liquid, an expansion chamber connected, with the upper portion of the cylinder and supported thereby,means for drawing off the liquid at a high level through the expansion chamber and for thereafter forcing it into the lower end of the cylinder below the piston to raise the latter and the piston rod, and the parts being so constructed and arranged that the movement of the piston is automatically lim-- ited as it approaches the upper end of the cylinder.

18. Hoisting mechanism comprising an upright cylinder having a lower end, an imperforate piston slidable in 'said cylin der, a hollow piston rod secured to said piston, an annular closure for the upper end of the cylinder, said piston rod projecting through the closure, a passage connecting the lower end of the rod with the space surrounding the rod above the piston, whereby the space both outside and inside of the piston rod may be used for the storage of liquid, means for drawing off the liquid at a high level' and for thereafter forcing it into the lower end of the cylinder below the piston to raise the latter and the piston rod, the inte- IIOI of said piston rod being in free and unobstructed communication with the atmosphere for at least a portion of its stroke, and means for automatically limiting the movement of the piston as it approaches the upper end of the cylinder. 19. Hoisting mechanism comprising a cyllnder having an upper end and a lower end, a closure for the upper end of the cylinder, a piston and piston rod slidable in the cylinder, said piston rod passing through the closure, means for forming an air chamber at the upper end of the cylinder of such shape that it conforms to and surrounds the upper end portion of the cylinder, said chamber being of size suflicient to allow expanslon of an amount'of liquid suflicient to fill a large proportion of the space inclosed by the cylinder, said air chamber forming means being supported by the cylinder, and pump means for drawing ofl' the liquid from above the piston through the air chamber and delivering it to the space in the cylinder below the piston whereby the piston rod is projected from the upper end of the cylinder.

20. Hoisting mechanism having an upright cylinder, a piston and piston rod slid- 30 a hollow piston rod slidable through said I -the cylinder near the upper end of the latter, means for clamping the tank in sealed able in the cylinder, sealing means for the upper end of the cylinder, the piston rod passing through the sealin means, said rod being of lesser diameter t an the cylinder whereby an annular storage space for liquid is formed, an expansion tank for liquid car-.

ried by the upper portion of the cylinder and in communication with the interior thereof, and means for drawing off the liquid in the upper end of the cylinder and expelling it below the piston to elevate the latter, whereby frothy liquid is retained in the expansion chamber and excluded from the liquid drawing and expelling means.

21. Hoisting mechanism including an upright cylinder, a piston and a piston rod slidable therein, means, including a pump,

connecting the upper portion of the cylinder with the space below the piston, sald cylinder and connecting means forming an endless loop system, exclusive of the pisis at thejupper limit of its movement.

22, Hoisting mechanism including an up right cylinder, havingan annular upper end,

, including a pump for drawing the liquid end and forming therewith a tight joint, an

imperforate piston fixed to the lower end of the rod, means, including a pump, connecting the upper end portion of the cylexpelling it into the cylinder below the piston to elevate the latter at Will.

24. Hoisting mechanism including a cylinder having an upper end and a lower end, a hollow piston rod slidable through the upper end and in sealed engagement therewith, an imperforate piston secured tothe rod, means for supplying liquid under pressure to the space below the piston to'elevate the latter and for continuouslydrawing said liquid from the upper end-portion of the cylinder when the piston reaches a predetermined elevation, the space below the piston being in communication with the atmosphere through the interior of the piston rod and independently of any communication through the lower portion of said space when the piston reaches said predetermined elevation. b 25. Hydraulic hoistingmechanism forming a circulatory system including a loop arranged with one end higher than the other, one branch-of the loop including an upright cylinder, a piston reciprocable in the cylinder, a piston rod projecting; upwardly from the piston, the other branch of the-loop including a suction pipe through which liquid may freely pass either from or to thespace above thepiston, the loop also through the suction pipe and forcing it"under pressure into the cylinder below the piston to elevate the latter, automath. means g for limiting the upward movement ofthe pistonrod, the system further including an inder with the space below the iston, said cylinder and connecting means orming an endless loop system through which liquid may "be circulated continuously when the piston reaches a predetermined elevation, thepiston rod and piston constituting two members, there being an opening through one of the members whereby communication is established between the lower end portion of the interior of the rod and the space be- I tween the rod and the cylinder, the parts being so constructed and arranged that both branches of the loop are in communication at'substantially the highest point in said" branches with the interior of the piston rod through said opening when the piston reaches the upper limitof its movement.

23. Hoisting mechanism comprising a cylinder having one end arranged above the other, a piston and piston rod slidable in the cylinder, an expansion tank surrounding relation with the cylinder to form a fluidtight joint therewith, there being a passage through the wall of the cylinder through means for drawing liquid from the tank and expansion space located for themost part above the upper limit of movement of the piston and exterior of the cylinder through which the liquid is drawn off to the suction pipe, said space'being large enough vto al- 105, low for the expansion of an amount of liquid suflicient to fill a large proportion of the. entire system and to separate the froth from said liquid under rapid and continuous circulation at high pressure. 26. In combination, an upright cylinder, a'piston slidable therein, a hollow piston rod connected to the piston and passing through the upper end of the cylinder, the interior of the piston rod being in communication with the space surrounding said rod above the piston, means for drawing liquid from the upper end portion of the cylinder andforcing it under pressure into the space below the piston ,to elevate the latter, auto- 'belng so constructed and, arranged that the space below the piston is in communication with the interior of the piston rod when'thepiston stands at the upper limit of its movement, and means for maintaining the pressure-on theupper surfaceof the liquid in the piston rod substantially equal to that of the atmosphere during at least the greater part of the stroke.

'27. In combination, an upright cylinder having an annular shoulder thereon, an expansion tank surrounding the cylinder and forming a'tight joint with said shoulder, an annular head for the upper end of the cylinder, a piston rod construction slidable through the head, said head being constructed and arranged to hold the tank against the shoulder.

28. In combination, an upright cylinder, a piston and a hollow piston rod slidable therein, an annular head for the upper end of the cylinder, the piston rod passing through the head in sealed relation therewith, the interior of the piston rod being in communication with the space between said piston rod and the cylinder and above the piston, means for forming a plugged passage through which liquid may be poured into the piston rod through the cylinder when the plug is removed, the upper end of the piston rod being in communication with the atmosphere at least when the piston rod is elevated, whereby the air therein may escape during the filling operation,

29. In combination, an upright cylinder, a piston and piston rod slidable therein, a combined lower end and supporting base for the cylinder, and means, including a pump attached to the base on the side thereof opposite the cylinder, for drawing off liquid from the upper end portion of the cylinder and expelling it through the base into the space between the base and the piston to elevate the latter.

In testimony whereof I sign this specification in the presence of two subscribing witnesses.

GARFIELD A. WOOD.

Witnesses:

L. M. SPENCER, MURLEN M. WOOD. 

